Beolingus - Two-way German-English dictionary with about 340,000 entries and several search options. From the Chemnitz University of Technology.
Canoo.net German Dictionaries - Meta-search of several dictionaries and a linguistic glossary. Allows lookup of keywords, linguistic terms, and affixes, and compound words.
Excavation Dictionary - Specialized two-way dictionary for archaeologists. Browsable by first letter only.
Foreign Language Master - Includes online Java and HTML versions as well as Windows and Amiga versions for download.
FreeDic - Birectional German-English dictionary with about 300,000 terms covering the most common vocabulary. From publisher Sprachendienst. Requires JavaScript.
How to Swear in German - Glossary of insults and swear words with English translations and sound files.
Library Glossary - Contains approximately 90,000 technical terms and abbreviations about libraries, books, and data processing.
LinguaDict - Allows two-way searches of over 512,000 entries. Includes several search options.
The New English-German Dictionary - Includes more than 200,000 translations, lists of strong verbs and abbreviations, and a Windows version for download.
QuickDic - Two-way word translator with several options. Windows version available for download.
Transgem - Technical online lookup which uses translated texts to provide corresponding meanings for words and phrases. Requires JavaScript.